How to create a trace outline animation of an object
General idea is to use Build modifier on Curve object.

If you have a model already, you can ...

Separate Ctrl+P a few loops into a new object
Convert to Curve
and Add Build modifier



Notes:

If you want to let all curve elements be animated at the same time you have to split them into separate objects.
Usually it is better to Separate mesh loops as lowpoly without Subdivision modifier, Convert to Curve, switch curve type to Bezier with Handles &gt; Automatic and manually adjust few end handles, so you have better control over additional curve shape adjustment. But like in this case it was easier to apply Subsurf modifier on separated mesh before Convert to Curve.
if you need more smooth animation increase curve resolution under Curve Properties

Based on TheGreens model.